Vehicle fuel systems include evaporative emission control systems designed to reduce the release of fuel vapors to the atmosphere. For example, vaporized hydrocarbons (HCs) from a fuel tank may be stored in a fuel vapor canister packed with an adsorbent which adsorbs and stores the vapors. At a later time, when the engine is in operation, the evaporative emission control system allows the vapors to be purged into the engine intake manifold for use as fuel.
Normal vaporization of the liquid fuel in the tank will cause the tank to become pressurized above atmospheric pressure. Prior to a refueling event, fuel tank vapor needs to be vented to the fuel vapor canister in order to prevent evaporative emissions via the fuel filler neck. Further, an over pressurized tank could result in liquid fuel splashing out of the tank when opened. Diverting fuel vapor located in the fuel tank to the fuel vapor canister prior to refueling is especially important for hybrid electric vehicles (HEVs), and other vehicles which feature a fuel tank isolation valve that seals the fuel tank in order to maintain fuel vapor within the tank during vehicle operations. In such a configuration, normal vaporization of the liquid fuel in the tank will cause the tank to become pressurized above atmospheric pressure as the liquid fuel warms.
In order to lower the fuel tank pressure to atmospheric pressure prior to refueling and therefore prevent fuel vapors from escaping into the atmosphere, HEVs come equipped with a dashboard-mounted refuel request button that a driver must press prior to refueling. One embodiment is disclosed by Lindlbauer et. al. in U.S. patent application 2015/0032307 A1. Requesting a refueling event triggers a controller to open the fuel tank isolation valve, depressurizing the fuel tank prior to allowing access to the fuel filler neck. However, the location of refuel request buttons on the vehicle instrument panel or dashboard is unintuitive and inconvenient. If a driver forgets to press the button prior to exiting the vehicle at the refueling station, he or she must re-enter the vehicle in order to prepare the vehicle for refueling. Further, a refueling operator approaching the refueling door from the outside of the vehicle has no control over the tank depressurization process.
The inventors herein have recognized the above described problems, and have developed systems and methods to at least partially address these issues. In one example, a method for a vehicle is presented, comprising: depressurizing a fuel tank while restricting access to a fuel fill line responsive to receiving a refueling request from a refueling request module located external to a vehicle cabin; and allowing access to the fuel fill line responsive to the fuel tank pressure decreasing below a threshold. In this way, all of the steps of a refueling procedure can be carried out entirely outside of a vehicle. For example, pushing a refueling door may initiate a depressurization of the fuel tank, and the status of depressurization may be indicated on one or more LED displays located either at or near the refueling door. During the fuel tank depressurization, the refueling door may be maintained locked, or the refueling door may open while a refueling inlet remains locked. By relaying the status of depressurization to an operator, any confusion on the part of the operator may be avoided. Further, the LED displays may be illuminated dynamically to indicate the fill level of the fuel tank, thereby providing a transparent system for the operator.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.